The present invention relates to an electrical outlet wiring analyzer. More particularly, the present invention relates to an electrical circuit for testing the electrical continuity and configuration of conductors of an electrical outlet as well as determining the impedance of one or more of the conductors when a half-cycle or full-cycle alternating current pulse, with a frequency corresponding to the frequency of a line alternating current voltage of the electrical outlet, is applied thereto.
Electrical outlets must be properly grounded. In addition, the conductors used in electrical outlets must be properly configured according to the particular applications of an outlet. Improper grounding and/or conductor configuration can lead to such problems as injury to personnel utilizing an outlet, damage to equipment connected to an outlet, and fire. One factor that contributes to poor grounding of an electrical outlet is the presence of impedance on the designated ground conductor of the outlet. Impedance contains both a resistive component and a reactive component. The reactive component varies with the frequency of the applied voltage and current. Thus, in order to obtain an accurate measure of ground conductor impedance for an electrical outlet, signals at the frequency of the line alternating current voltage must be applied to the ground conductor. Signals at other frequencies will yield different and inaccurate ground conductor impedance values for an electrical outlet.
Different designs for electrical outlet wiring analyzers exist. One such design is known as a three-lamp outlet circuit tester. One problem with three-lamp outlet circuit testers is that they reveal nothing about the quality of the grounding conductor (i.e., the amount of impedance on the ground conductor). Problems with other designs include such things as improper measurement of conductor impedance (i.e., not measuring ground conductor impedance at the frequency of the line alternating current voltage) and general difficulty of use. An outlet wiring analyzer that solved the problems associated with the above-described designs would be a welcome improvement.
Accordingly, an electrical outlet wiring analyzer is provided. The wiring analyzer includes circuitry for verifying electrical continuity and for determining polarity of conductors of an electrical outlet. Voltage controlled switch circuitry is electrically connected in series with the electrical continuity verifying and polarity determining circuitry. The voltage controlled switch circuitry prevents the electrical continuity verifying and polarity determining circuitry from operating with an electrical potential difference less than an electrical trigger potential difference of the voltage controlled switch circuitry. The voltage controlled switch circuitry may include a sidac. Circuitry for determining the impedance of at least one of the conductors at the frequency of the alternating current voltage supplied by the electrical outlet or the potential difference between at least one conductor and a reference conductor is also provided.
In one embodiment, the electrical continuity verifying and polarity determining circuitry includes a light emitting diode electrically connected in parallel with circuitry for preventing the reverse bias of the light emitting diode and circuitry for diverting current from the light emitting diode to prevent false indications of electrical continuity and polarity of the conductors due to leakage current from items electrically connected to one or more of the conductors. The circuitry for diverting current may include a resistor and the circuitry for preventing reverse bias of the light emitting diode may include a diode having an anode electrically connected to a cathode of the light emitting diode and a cathode electrically connected to an anode of the light emitting diode.
The electrical outlet wiring analyzer may find application in an electrical outlet having three conductors: a hot conductor, a neutral conductor, and a ground conductor. In such application, the electrical outlet wiring analyzer would have electrical continuity verifying and polarity determining circuitry and voltage controlled switch circuitry electrically connected between each of the hot and the neutral conductors, the hot and the ground conductors, and the neutral and the ground conductors.
Another embodiment of the electrical outlet wiring analyzer includes impedance determining circuitry for determining an impedance of at least one electrical conductor of an electrical outlet, having a plurality of conductors, at the frequency of the alternating current voltage supplied by the electrical outlet. In this embodiment, the electrical outlet wiring analyzer also includes connecting circuitry for connecting at least one of the conductors of the electrical outlet to the impedance determining circuitry. The impedance determining circuitry may utilize an alternating current pulse of one cycle at a frequency of the alternating current voltage to determine the impedance of the conductor to which the current pulse is applied. Alternatively, the impedance determining circuitry may utilize a current pulse of one-half cycle at a frequency of the alternating current voltage to determine the impedance of the conductor to which the current pulse is applied. The electrical outlet wiring analyzer may further include circuitry for determining a potential difference between at least one conductor and a reference conductor. The potential difference determining circuitry may determine both the positive and negative potential difference between the conductors.
Another embodiment of the electrical outlet wiring analyzer includes generator circuitry for periodically providing an alternating current pulse of one cycle at a frequency of an alternating current voltage supplied by an electrical outlet that has a plurality of conductors. In this embodiment, the electrical outlet wiring analyzer also includes connecting circuitry for electrically applying the alternating current pulse to at least one of the conductors and impedance determining circuitry for determining the impedance of each of the conductors to which the alternating current pulse is applied. This embodiment of the electrical outlet wiring analyzer may find application in an electrical outlet having three conductors: a hot conductor, a neutral conductor, and a ground conductor. For such an electrical outlet, the connecting circuitry would selectively apply the alternating current pulse to the ground or neutral conductors. The electrical outlet wiring analyzer may also have a jack for electrically attaching to a remote ground conductor. In this embodiment, the connecting circuitry would selectively apply the alternating current pulse to either the neutral, ground, or remote ground conductors.
In one embodiment, the generator circuitry of the electrical outlet wiring analyzer includes a zero-voltage switch crossing circuit, a timer, a push button switch, and a current controlled switch. The zero-voltage switch crossing circuit is electrically connected to the timer and the push button switch is electrically connected between the zero-voltage switch crossing circuit and the timer. The current controlled switch is electrically connected to the alternating current voltage supplied by the electrical outlet, the connecting means, and an output of the zero-voltage switch crossing circuit. The output of the zero-voltage switch crossing circuit enables the current controlled switch for one cycle of the alternating current voltage. This embodiment of the generator circuitry may include circuitry for limiting the magnitude of the alternating current pulse electrically connected between the current controlled switch and the connecting means. The alternating current pulse magnitude limiting circuitry may include a resistor and the current controlled switch may include a triac. A gate of the triac may be electrically connected to an output of the zero-voltage switch crossing circuit, a main terminal 1 of the triac may be electrically connected to the resistor, and a main terminal 2 of the triac may be electrically connected to the alternating current voltage. Thermal overload circuitry may be included for preventing thermal overload of the alternating current pulse magnitude limiting circuitry.
The electrical outlet wiring analyzer may include circuitry for indicating the application of the alternating current pulse to the selected conductor. The alternating current pulse application indicating circuitry may be electrically connected in parallel with the alternating current pulse magnitude limiting circuitry. The alternating current pulse application indicating circuitry may include voltage controlled switch circuitry electrically connected in series with a light emitting diode that is electrically connected in parallel with both circuitry for preventing reverse bias of the light emitting diode and circuitry for diverting current from the light emitting diode to prevent false indications of the application of the alternating current pulse due to current from items electrically connected to the conductors. The voltage controlled switch circuitry prevents operation of the light emitting diode with an electrical potential difference less than an electrical trigger potential difference of the voltage controlled switch circuitry. In one embodiment, the voltage controlled switch circuitry includes a sidac and the light emitting diode reverse bias preventing circuitry includes a diode, and the current diverting circuitry includes a resistor. The diode has an anode electrically connected to a cathode of the light emitting diode and a cathode electrically connected to an anode of the light emitting diode.
The connecting circuitry may include a switch. The impedance determining circuitry may include circuitry for indicating an impedance value, voltage controlled switch circuitry for controlling the enabling of the impedance value indicating circuitry, circuitry for supplying a regulated voltage to both the impedance value indicating circuitry and the voltage controlled switch circuitry, and voltage divider circuitry for providing at least two different voltages to the voltage controlled switch circuitry. The voltage controlled switch circuitry is electrically connected to the impedance value indicating circuitry and the voltage divider circuitry. The voltage divider circuitry is electrically connected to the conductor to which the alternating current pulse is applied. The voltage controlled switch circuitry may include metal oxide silicon field-effect transistors each having a drain, a source, and a gate. The sources of the metal oxide silicon field-effect transistors may be electrically connected to the regulated voltage supplying circuitry. The gates of the metal oxide silicon field-effect transistors may be electrically connected to the voltage divider circuitry. The impedance value indicating circuitry may include light emitting diodes having anodes which are electrically connected to the regulated voltage supplying circuitry and cathodes which are electrically connected to the drains of the metal oxide silicon field-effect transistors.
In one embodiment of the impedance determining circuitry, the voltage divider circuitry includes two separate sets of resistors. A first set of resistors is connected to gates of N-channel metal oxide silicon field-effect transistors. The first set has circuitry for applying only a positive half-cycle of the alternating current pulse to the gates of the N-channel metal oxide silicon field-effect transistors. A second set of resistors is connected to the gates of P-channel metal oxide silicon field-effect transistors. The second set of resistors has circuitry for applying only a negative half-cycle of the alternating current pulse to the gates of the P-channel metal oxide silicon field-effect transistors. The circuitry for applying only the positive and negative half cycles of the alternating current pulse may include diodes.
In another embodiment of the impedance determining circuitry, the regulated voltage supplying circuitry includes first regulator circuitry that supplies regulated power to N-channel metal oxide silicon field-effect transistors during a positive half-cycle of the alternating current voltage supplied by the electrical outlet and second regulator circuitry for supplying regulated power to P-channel metal oxide silicon field-effect transistors during a negative half-cycle of the alternating current voltage supplied by the electrical outlet. The circuitry for the first and second regulators may include a resistor, a diode, and a zener diode.
The impedance value indicating circuitry may indicate the impedance value during both a positive and negative half-cycle of the alternating current pulse. In addition, the impedance value indicating circuitry may indicate the electrical potential difference between the conductor to which the alternating current pulse is applied and a reference conductor prior to and subsequent to the application of the pulse. Both the conductor to which the alternating current is applied and the reference conductor are selected by the connecting means. In one embodiment, both the positive and negative electrical potential differences between the conductors is indicated.
The electrical outlet wiring analyzer having at least the generator circuitry, connecting circuitry, and impedance determining circuitry may further include the above-described circuitry for verifying electrical continuity and for determining polarity of the conductors of the electrical outlet.
Another embodiment of the electrical outlet wiring analyzer includes pulser circuitry for periodically providing an current pulse of one-half cycle at a frequency of the alternating current voltage supplied by an electrical outlet that has a plurality of conductors. In this embodiment, connecting circuitry for electrically applying the current pulse to at least one of the conductors is provided. Circuitry for determining an impedance of the conductors to which the current pulse is applied is also provided.
The electrical outlet wiring analyzer of this embodiment may find application with an electrical outlet having three conductors: a hot conductor, a neutral conductor, and a ground conductor. In such an embodiment, the connecting means selectively applies the current pulse to either the neutral or ground conductors.
In one embodiment, the pulser circuitry includes a timer, a zero-voltage crossing opto-coupler, and a current controlled switch. The current controlled switch is electrically connected to an output of the zero-voltage crossing opto-coupler, the alternating current voltage supplied by the electrical outlet, and the connecting means. An output of the zero-voltage crossing opto-coupler enables the current controlled switch for one cycle of the alternating current voltage so that the current controlled switch outputs a half-wave current pulse. The electrical outlet wiring analyzer may also include circuitry for limiting the magnitude of the current pulse. This circuitry is electrically connected between the current controlled switch and the alternating current voltage. In one embodiment, the current pulse magnitude limiting circuitry includes a resistor and the current controlled switch includes a silicon controlled rectifier. A gate of the silicon controlled rectifier is electrically connected to the output of the zero-voltage crossing opto-coupler. An anode of the silicon controlled rectifier is electrically connected to the resistor and a cathode of the silicon controlled rectifier is electrically connected to the connecting means.
Circuitry for indicating the application of the alternating current pulse may also be provided. The current pulse application indicating circuitry is electrically connected in parallel with the current pulse magnitude limiting circuitry. The current pulse application indicating circuitry may include voltage controlled switch circuitry that is electrically connected in series with a light emitting diode electrically connected in parallel with both circuitry for preventing reverse bias of the light emitting diode and circuitry for diverting current from the light emitting diode to prevent false indications of the application of the current pulse due to current from items electrically connected to the conductors. The voltage controlled switch circuitry prevents the operation of the light emitting diode with an electrical potential difference less than an electrical trigger potential difference of the voltage controlled switch circuitry. The voltage controlled switch circuitry may include a sidac. The light emitting diode reverse bias preventing circuitry may include a diode, and the current diverting circuitry may include a resistor. The diode has an anode electrically connected to a cathode of the light emitting diode and a cathode electrically connected to an anode of the light emitting diode.
The connecting means of the electrical outlet wiring analyzer may include a switch. The impedance determining means may include circuitry for indicating an impedance value, voltage controlled switch circuitry for controlling the enabling of the impedance value indicating circuitry, circuitry for supplying a regulated voltage to both the impedance value indicating circuitry and the voltage controlled switch circuitry, and voltage divider circuitry for providing at least two different voltages to the voltage controlled switch circuitry. In this embodiment, the voltage controlled switch circuitry is electrically connected to the impedance value indicating circuitry and the voltage divider circuitry. The voltage divider circuitry is electrically connected to the conductor to which the current pulse is electrically applied. The voltage controlled switch circuitry may include metal oxide silicon field-effect transistors each having a drain, a source, and a gate. The sources of the metal oxide silicon field-effect transistors may be electrically connected to the regulated voltage supplying circuitry. The gates of the metal oxide silicon field-effect transistors may be electrically connected to the voltage divider circuitry. The impedance value indicating circuitry includes light emitting diodes. The anodes of the light emitting diodes are electrically connected to the regulated voltage supplying circuitry and the cathodes of the light emitting diodes are electrically connected to the drains of the metal oxide silicon field-effect transistors.
The electrical outlet wiring analyzer that produces only a half-cycle current pulse may also include the above-described circuitry for verifying electrical continuity and for determining polarity of the conductors of the electrical outlet.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.